Multi-function peripheral devices have a plurality of functions, such as a printer function and a scanner function. In relation to such multi-function peripheral devices, JP-A-8-149178 describes a technique to monitor use statuses of respective functional blocks. Then, an operational state of a functional block which has not been utilized for a given period is changed from a normal state to a standby state. When the functional block is changed to the standby state, application of power to the functional block is reduced, and hence the power consumed by the entire device can be saved.
In order to connect a multi-function peripheral device and a personal computer (PC) so that a user can operate the multi-function peripheral device with the PC, no alternative way exists other than to connect with a certain cable to certain interfaces (e.g., a Centronics interface) that is provided only one in each of the PC and the multi-function peripheral device. In conjunction with recent improvement in communications technology, various communication schemes, including radiocommunication, have been put into practical use, and a PC or a multi-function peripheral device has been provided with a plurality of interfaces. As a result, a user has become able to select an optimum interface (a connection method) according to a user's use environment. However, even when a plurality of interfaces are provided between the PC and the multi-function peripheral device, an interface used for connection between the PC and the peripheral device is usually one. Therefore, other interfaces than the used interfaces might wastefully consume power.
According to the technique described in JP-A-8-149178, the functional block is changed to the standby state to suspend the operation of the functional block, thereby saving power consumption. However, in order to utilize the function in standby state, operation for changing the function into a normal condition is required. Therefore, the function can not be used immediately.